Fiberglass vs. Steel Rebar: Which is Best for Structural Reinforcements?

Structural reinforcements are imperative for the overall strength and longevity of concrete-based structural applications such as bridge decks, parking garages and drainage systems. Reinforcements are indispensable for retrofitting existing structures while being more cost-effective than rebuilding them, especially in terms of increasing the load-bearing capacity of the original structure. Traditionally, the structural industry has used steel to produce structural reinforcements.

This blog post will highlight the shortcomings of steel-based reinforcements and why fiberglass is the best structural reinforcement material today.

Steel rebars

Steel rebars, short for reinforcement bars, are traditional structural reinforcements typically used for reinforcing cement concrete. Concrete is strong under compressive loads but weak under tensile loads. Steel rebars hold the concrete together and enhance the tensile strength of concrete-based structures while preventing cracks in structural components during tensile loading. Steel was used in rebars primarily because its thermal expansion is similar to concrete.

Unfortunately, steels are highly reactive. Steel slowly starts corroding as concrete comes in contact with oxygen, chlorides and moisture. Corrosion eats up steel and compromises the strength of structural reinforcements, making them failure-prone. Over time, rust accumulates on steel bars and builds up pressure on the surrounding concrete, leading to cracks that can eventually fracture concrete via spalling. These failures are costly to repair and maintain. Moreover, steel rebars are susceptible to melting at increased temperatures, are excessively heavy and are expensive to install.

Fiberglass - The Future of Structural Reinforcements

Fiberglass, aka fiberglass-reinforced polymers, is a composite material containing a polymer resin matrix reinforced by embedded glass fibers. They are easy to fabricate and are manufactured via pultrusion. 

Fiberglass overcomes the main shortcomings of steel rebars and is unquestionably the modern go-to material for structural reinforcements. Fiberglass fabrics are lightweight with a high strength-to-weight ratio, flexural strength and stiffness. Fiberglass is roughly 75-80% lighter than steel and yet possesses higher strength and requires less installation time and labor.

Less weight is thus added to the reinforced structures, enhancing their performance. Fiberglass is easily transformed into complex shapes, offering higher flexibility for custom applications. Unlike steels, fiberglass is highly chemically resistant, especially to corrosion. The interwoven structure of fiberglass makes structural reinforcements impervious to water and other corrosive and alkaline environments. Fiberglass reinforcements require minimal maintenance and have low lifecycle costs. Fiberglass is electrically non-conductive and therefore ensures personnel safety.

Fiberglass Reinforcements from Strongwell

With over 65 years of experience, Strongwell is a “gold standard” in delivering a wide variety of structural engineering solutions. We offer the following cost-effective, state-of-the-art fiberglass structural reinforcements:


  1. GRIDFORM™: Prefabricated fiberglass structural reinforcement with double-layer grating and an integral stay-in-place form. It is designed to replace steel rebars for reinforcing concrete vehicular bridge decks. Its unique double-layered structure creates a bidirectional, lightweight panel for grid construction. GRIDFORM™ is very lightweight, weighing only 4.7 pounds per square foot. It is easily attachable to the bridge girders and allows hassle-free concrete filling and forming. Due to its corrosion resistance, GRIDFORM™ structural reinforcements live much longer than steel rebars.
  2. SAFSTRIP®: A cost-effective composite strengthening strip made from carbon tows sandwiched between layers of rovings and fiberglass mats. It significantly improves the flexural and load-bearing capacity of the tensile face of structures such as concrete decks, girders and slabs. SAFSTRIP® structural reinforcements are straightforward to install using mechanical fastening to existing structural members with minimal surface preparation. The strips allow drilling without splitting or delaminating.
  3. SAFSTRIP® Carbon: A unidirectional fiberglass-based structural reinforcement comprising of high modulus and high tensile strength carbon fibers embedded in a thermoset resin. It is exclusively designed to be used as an externally applied reinforcement for structural strengthening of concrete, masonry and timber structures. Its target applications include seismic and structural strengthening, fixing damaged structural parts, and design or construction defects. Thanks to its thin profile, it hardly impacts aesthetics.


Contact us today to find the right product for your project from our wide range of structural reinforcements solutions.